New to PLCs and need help finding a PLC and some Sensors.

Hi All,



Basically, I am fairly new to PLCs. I have only programmed a couple. My main background is computer networking and computer programming.



I have been tasked with developing a new control set for our machines, which incorporates a PLC. We are an OEM that builds machines that generate ozone and mix it with water. We need to analyze several things such as oxygen concentration, air flow, air pressure, as well as taking in 4-20ma signals and sending a 4-20ma signal out to the generator via a PID. I have outlined basic requirements for the system in the attached PDF document.



We are looking to put the appropriate PLC into every machine that we sell.



Although I could use some advise as far as what company to go with and what PLC to obtain, what I am having the most difficulty with is sourcing out sensors for our particular need. I've tried googling to no avail.



I need an oxygen concentration sensor that operates from 20-99% at air flow rates of 5 - 60 SCFH. This sensor can either be a switch that comes on at 90%, or sends a 4-20ma signal to the PLC.



I also need an airflow sensor that measures a range of 5-60 SCFH and outputs a 4-20ma. This could be a switch as well, but I would need to stock several models of the airflow switch since our different size generators operate at different airflow rates.



Along the same premise, I need an air pressure sensor that outputs a 4-20ma along a range of 0-20 psi.



An economical air temperature sensor, both for ambient air and inline air, is also needed.



The above four sensors are just for the machine control aspect. In the future I want to expand to an additional PLC that contains a program for monitoring water quality and it's associated sensors. I have yet to be able to find a direct manufacturer for ORP, pH, Temp, Flow, Conductivity/TDS, and Influent/Effluent pressure sensors for water.



I need the control PLC to store a log of machine alarms and operation data, call out to a cell phone/pager, and to be able to dial into the unit as see the data of machine operation in real time. I also need an easy to use, programmable display. http://c-more.automationdirect.com/ Looked pretty cool.



Anyways, please give me your thoughts on what I should look at. If I missed information, please let me know and I will post it.


Thanks!

Ray.

I haven't accessed your pdf yet, but sounds like a good match for Entertron PLC's. They have FREE software and support. They have a GSM modem, and also a LoggeR for downloading to excell lots of info. They are ideal for OEM applications, 'specially if you want to keep the program prorietory, and not give it out.

You can find them "LINK", and when you call, ask for Stephen, tell him you heard about them on plcs.net.

regards.....casey

Thanks casey.

What about sensors?
Ray.

Here are a couple of places to look at sensors etc:
http://www.omega.com/

http://www.davis.com/showl5.asp?L5ID=5

As for the PLC itself that could depend. I think I would look at AB compactlogix or contrologix for a new or upgrade project http://www.ab.com/logix/compactlogix/

A less expensive option may be Automation Direct products www.automationdirect.com.

Fact is that most brands can do what you have asked about, the issue is finding matching appropriate sensors to inputs etc. Look closely at the Omega products and I am sure others will offer more.

If you go with a modular/rack style PLC and do the homework you may be able to expand with just adding the necessary I/O.

I can't help on the sensors, never used any like that before.
There are a couple guys on here that know them pretty well, and will probably check in.

Now, if you have an unlimited budget, we can recommend an expensive plc and a distributor who will get top $$$ for sensors...

www.globalspec.com

Nail down the specs on your sensors & see what the world has.

Sometimes the Grainger or Johnston or McMaster supply catalogs work very well for finding stuff - at least a starting point for price and general configuration.

And of course there is Google ie "oxygen detectors".
BTW you did mean oxygen detector with range up to 99% and not ozone??
The higher end of your desired range is going to be a challenge I think.

Try Vaisala they have quite a few sensors for HVAC and other "air" applications.

Flow sensors will generally maasure only velocity ie feet per minute (FPM). Volumetric (SCFM) is derived by FPM x duct cross section area.
Kurtz makes a pretty wide selection of air flow sensors - so does Vaisala I think.

That otta keep you busy for an hour or so.

Dan Bentler

for you pressure sensor check out Dwyer..they make some nice units.. Also is the water you are ozinating for consumption? If so then i guess all the sensors would be Stainless steel??

D

Thanks for the replys guys.

The sensors will not have to be stainless steel. All these sensors will be mounted "pre ozone" inside of the machine. We use an oxygen concentrator along with an oiless compressor, that concentrates the oxygen to very high levels. Since ozone is created from oxygen, the higher your oxygen concentration the better. Our current oxygen concentrators that we use typically get 92-96% concentration. That oxygen gets passed straight into the ozone generator, and then the corona discharge goes directly into the water via venturi.

I will be mounting all of the sensors at the output of the concentrator, before the ozone generator. The oxygen concentration sensor will be used to tell the operator if the concentrator is working effectively. The pressure and air flow will be able to detect if the ozone generator is being fed the proper amount of air at the right pressures. These 3 sensors will be able to tell me if the concentrator goes bad, or if the compressor fails, and if there is a leak in the line. (Ozone generators typically have pressure regulators internally that usually "step down" the pressure going into the plates)

I didn't mean to say 99% ozone. In my experience, corona discharge can usually only get at most 10% of the total air volume of ozone. 99% would be amazing!

I tried looking at McMaster, and others such as Ryan Herco and Harrington, and they don't really have what I need. I don't need $250-$1000 instruments. I am really just looking for a simple electronics board or switch that I can tuck away into the control box, and just interface it with the PLC. Cost is an issue.

I went to globalspec and sent e-mails to various manufacturers. I hope I get some replies.

Any idea what Kurtz's URL is? I can't seem to find them by googling.

Also, I checked out Visalia and I can't find oxygen concentration sensors in their product line.

Hate to burst your bubble but with most of the sensors you spec I dont think you are going to get much below the $250 mark...

Here is an E-mail I got from our oxygen concentrator supplier. I attached an image. This chip is all I need, but the $300 price tag seems a bit much for what it is:

"What we have is an oxygen monitor which has oxygen alarms at Above 85% green light and output to DB9 connector Between 70% and 84%, amber light and output to DB9 connector Below 69%, red light and output to DB9 connector

Also, two of the pins on the connector have 0-1 Volts DC, corresponding to 0-100% concentration. That information can be brought out and the logic used to open or close a solenoid valve, if you knew how to do that.

The images and information for the board are attached."

But on the downside it can only handle up to 20 SCFH.

SCFH??
First time with that one..

darrenj said:

SCFH?? First time with that one..

Click to expand...

Southern California Faggot Horseflies, unless I miss my guess!

CaseyK said:

Southern California Faggot Horseflies, unless I miss my guess!

Click to expand...

SCFH Standard Cubic Feet per Hour
SCFM Standard Cubic Feet per Minute
generally I have seen SCFM most often.

Casey are you sure them flies are equal opportunity to Faggot and horses?? Not very discriminating are they?

I agree with Darren for your purposes you are not going to get away with less than 200 for ANY detector with any kind of precision.

Try Kurz for the air flow sensor maybe I mispelled.

Check with Mine Safety Appliance for the oxygen detector - a bit out of their normal "work" or product line but who knows? Maybe they will refer you to their vendor if they don't make their own.

Dan Bentler